I am new to openCV. I am going to write a program to retrieve the best matched image from the image database given an input image. However, I found that the accuracy is quite low. A low percentage of images can be correctly matched from the database. The program can run, but I am not satisfied with that.
What are the problems in the algorithm? Which parts do I need to improve? And how can I improve it? Thanks guys.
#include "opencv2/highgui/highgui.hpp"
include "opencv2/imgproc/imgproc.hpp"
include <iostream>
include <stdio.h>
include <algorithm>
using namespace std; using namespace cv;
define IMAGE_LIST_FILE "inputimage.txt"
/** * @function main */
//Compute pixel-by-pixel difference double compareImgs(Mat img1, Mat img2) { int w = img1.cols, h = img2.rows; Mat new_img2; resize(img2, new_img2, img1.size()); double sum = 0; for (int i = 0; i < w; i++)for (int j = 0; j < h; j++) { sum += abs(img1.at<uchar>(j, i) - new_img2.at<uchar>(j, i)); } return sum; }
int main( int argc, char** argv ) { Mat src_input, gray_input; Mat db_img, db_gray_img;
double score[1000];
int db_id = 0;
double maxscore = 1000000000;
int maxscore_num;
char maximg_name[200];
Mat max_img;
src_input = imread("dinosaur.jpg"); // read input image
if( !src_input.data )
{
printf("Cannot find the input image!\n");
system("pause");
return -1;
}
imshow("Input",src_input);
/// Convert to grayscale
cvtColor(src_input, gray_input, COLOR_BGR2GRAY);
///Read Database
FILE *fp;
char imagepath[200];
fp = fopen( IMAGE_LIST_FILE, "r ");
printf("Extracting features from input images...\n");
while(!feof(fp))
{
while(fscanf(fp, "%s ", imagepath) > 0)
{
printf("%s\n",imagepath);
char tempname[200];
sprintf_s(tempname,200,"../%s",imagepath);
db_img = imread(tempname); // read database image
if( !db_img.data )
{
printf("Cannot find the database image number %d!\n",db_id+1);
system("pause");
return -1;
}
cvtColor(db_img, db_gray_img, COLOR_BGR2GRAY);
/// Apply the pixel-by-pixel comparison method
score[db_id] = compareImgs(gray_input, db_gray_img);
/// Compute max score
if(score[db_id]<maxscore)
{
maxscore=score[db_id];
maxscore_num = db_id;
memcpy(maximg_name,tempname,200*sizeof(char));
}
db_id++;
}
}
fclose(fp);
Mat maximg = imread(maximg_name);
imshow("Best Match Image",maximg);
printf("the most similar image is %d, the pixel-by-pixel difference is %f\n",maxscore_num+1, maxscore);
printf( "Done \n" );
// Wait for the user to press a key in the GUI window.
//Press ESC to quit
int keyValue=0;
while(keyValue>=0)
{
keyValue=cvWaitKey(0);
switch(keyValue)
{
case 27:keyValue=-1;
break;
}
}
return 0;
}
